A plant community on an extinct volcano displays the process of succession. Explain why there would be very few species at the end of the eruptive life cycle of the volcano and why rate of new species introduction would rapidly increase afterwards.

The initial environment would be a harsh/hostile environment which few species would be adapted to. The volcanic rock would have to be broken down to form humus, only a little or none would have been available.

After the pioneer species break down the rock into humus/soil, primary coloniser plants are able to establish roots. After they die and decompose, they add to the organic matter of the soil, nitrate content and allow more plants to grow.